What day of the week you want to fly will determine how much you pay for your seat. Most often, you'll find the best fares -- for both domestic and international flights -- fall on Tuesdays and Wednesdays, the two most unpopular days of the week to travel. Think about it: Most people start their vacations on the weekends, and business travel booms on Mondays and again at the end of the week, leaving Tuesdays and Wednesdays for those who can be a little flexible with their schedule.
Smart travelers take advantage of that decreased demand for seats on Tuesdays and Wednesdays to score good ticket prices. By traveling on those days they get an additional perk: Fewer fellow passengers means shorter lines at the airport.